Identifying and troubleshooting battery problems (VW Golf 5)

Too low capacity. Voltage drops sharply

The battery is discharged

Recharge the battery.

Charging voltage too low

Check the voltage regulator, replace if necessary.

The connecting terminals are loose or oxidized

Clean the terminals and tighten the clamp bolts.

Bad ground connection (-) battery-engine-body

Check connections, install new wire if necessary, tighten bolted connections. Replace rusty bolts with tin-plated bolts.

Excessive self-discharge of the battery due to contamination of the electrolyte

Replace the battery.

Battery sulfation

Charge the battery with a small current. If the power remains low after charging, replace the battery.

The battery has served its time. The active mass of the plates has precipitated.

Replace the battery.

Insufficient battery charge while driving

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The generator, voltage regulator or connecting wires are faulty

Check the alternator and voltage regulator. Repair or replace if necessary.

The V-belt is loose. The tensioner is faulty

Check the tensioner. Replace the V-belt if necessary.

Too many current consumers are connected to the on-board network

Install a battery with a higher capacity or install a more powerful generator.

Low electrolyte level*

Overload, evaporation (especially in summer)

Add distilled water to the specified level (with a charged battery).

Electrolyte density too low*

The battery is discharged

Charge the battery.

Short circuit in the on-board electrical system

Check the vehicle's electrical system.

The density of the electrolyte in one cell is significantly lower than in the others*

Compartment short circuit

Replace the battery.

The density of the electrolyte in the two adjacent compartments is significantly lower than in the others

The cell's dividing wall is not hermetically sealed, leading to constant discharge

Replace the battery.

* these items apply to conventional batteries.